Transfer large files/directories with no overhead, over the network
# ssh user@host "cd targetdir; tar cfp - *" | dd of=file.tar
Causes traffic lights to flash on the nic
# ethtool -p ethX
Watch Data Usage on eth0
# watch ifconfig eth0
netcat as a portscanner. Show open ports.
# nc -v -n -z -w 1 127.0.0.1 22-1000
Lists all listening ports together with the PID of the associated process
# netstat -tlnp
what's running on a given port on your machine
# lsof -i -n -P | grep :22
Start a tunnel from some machine's port 80 to your local post 2001
now you can access the website by going to http://localhost:2001/
# ssh -N -L2001:localhost:80 somemachine
If you want to connect to server behind the DMZ, you can use a intermediate. This is useful where your have your local machine outside a firewall; a visible machine on the DMZ; and a third machine invisible to the outside.
# ssh -f -N -q -L 80:192.168.1.69:80 username@dmz.example.com
The params explaination: